Re: [V10 1/8] ACPI: Add support for AMD ACPI based Wifi band RFI mitigation feature

On Fri, Aug 25, 2023 at 04:38:39PM +0800, Evan Quan wrote:

Due to electrical and mechanical constraints in certain platform designs
there may be likely interference of relatively high-powered harmonics of
the (G-)DDR memory clocks with local radio module frequency bands used
by Wifi 6/6e/7.

To mitigate this, AMD has introduced a mechanism that devices can use to
notify active use of particular frequencies so that other devices can make
relative internal adjustments as necessary to avoid this resonance.

Signed-off-by: Evan Quan <redacted>

...

...

+/**
+ * acpi_amd_wbrf_add_exclusion - broadcast the frequency band the device
+ *                               is using
+ *
+ * @dev: device pointer
+ * @in: input structure containing the frequency band the device is using
+ *
+ * Broadcast to other consumers the frequency band the device starts
+ * to use. Underneath the surface the information is cached into an
+ * internal buffer first. Then a notification is sent to all those
+ * registered consumers. So then they can retrieve that buffer to
+ * know the latest active frequency bands. The benifit with such design

nit: ./checkpatch.pl --codespell suggests benifit -> benefit.

+ * is for those consumers which have not been registered yet, they can
+ * still have a chance to retrieve such information later.
+ */
+int acpi_amd_wbrf_add_exclusion(struct device *dev,
+				struct wbrf_ranges_in_out *in)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+	int ret;
+
+	if (!adev)
+		return -ENODEV;
+
+	ret = wbrf_record(adev, WBRF_RECORD_ADD, in);
+	if (ret)
+		return ret;
+
+	blocking_notifier_call_chain(&wbrf_chain_head,
+				     WBRF_CHANGED,
+				     NULL);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_amd_wbrf_add_exclusion);

...